The correct answer is man-in-the-middle attacks because the certificate cannot be verified. A self-signed TLS certificate is not issued by a trusted Certificate Authority (CA), so a client’s browser or application has no way to confirm the certificate’s authenticity during the TLS handshake. This opens the door for an attacker to intercept the connection, present their own self-signed certificate, and silently decrypt, read, or modify the data in transit—the core of a man-in-the-middle vulnerability. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your understanding of certificate trust chains and encryption integrity; a common trap is assuming encryption alone is sufficient, forgetting that unverified certificates break the authentication pillar of the CIA triad. Remember the mnemonic: “Self-signed = trust-blind,” meaning no external authority means no verification, and no verification means MITM is wide open.
ISC2 CC Security Operations Practice Question
This CC practice question tests your understanding of security operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company's security policy requires that all sensitive data be encrypted during transfer. A security administrator discovers that an internal web application is using a self-signed TLS certificate. What vulnerability does this introduce?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Man-in-the-middle attacks because the certificate cannot be verified
A self-signed TLS certificate is not signed by a trusted Certificate Authority (CA), so clients cannot verify the certificate's authenticity. This allows an attacker to intercept the TLS handshake, present their own self-signed certificate, and perform a man-in-the-middle (MITM) attack, decrypting and reading or modifying the data in transit.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Data corruption
Why it's wrong here
Self-signed certificates do not cause data corruption.
✗
Increased latency
Why it's wrong here
Latency is not a security vulnerability introduced by self-signed certificates.
✗
Replay attacks because TLS is not used
Why it's wrong here
TLS is used (the certificate is for TLS), so replay attacks are mitigated.
✓
Man-in-the-middle attacks because the certificate cannot be verified
Why this is correct
Without a trusted CA, clients cannot confirm the server's identity, allowing interception.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the misconception that self-signed certificates mean TLS is not used, but the trap here is that TLS is still active; the real issue is the lack of certificate validation, which opens the door to MITM attacks.
Detailed technical explanation
How to think about this question
During a TLS handshake, the server presents its certificate, and the client checks the certificate's signature against a trusted root CA store. With a self-signed certificate, the client receives no chain of trust, so unless the client is explicitly configured to trust that specific certificate (e.g., via certificate pinning), it cannot authenticate the server. In a real-world scenario, an attacker on the same network can use tools like mitmproxy or BetterCAP to intercept the connection, present their own self-signed certificate, and the client will accept it if certificate validation is disabled or ignored, allowing full decryption of traffic.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC question in full detail.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Man-in-the-middle attacks because the certificate cannot be verified — A self-signed TLS certificate is not signed by a trusted Certificate Authority (CA), so clients cannot verify the certificate's authenticity. This allows an attacker to intercept the TLS handshake, present their own self-signed certificate, and perform a man-in-the-middle (MITM) attack, decrypting and reading or modifying the data in transit.
What should I do if I get this CC question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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